The 60-foot long buses were supposed to run for 12 years and about 500,000 miles. But after only four years and relatively few miles, the buses were cracking, due to a defect in the fastening system that connects the front and back sections.

So the CTA pulled the buses, which made up about six percent of the entire fleet, fortunately before any serious problems occurred.

On Thursday, North American Bus Industries, the buses' manufacturer, voluntarily recalled the vehicles in question in an effort to inspect and repair them.

"Given the six-year performance history of these buses, concerns about their long-term structural integrity and ongoing litigation with the manufacturer, it does not make sense to expend any more of our limited resources on these buses," CTA President Richard Rodriguez told the Tribune.

The "ongoing litigation" Rodriguez refers to is the battle in Cook County Circuit Court between the CTA and NABI.

According to the CTA, the agency knew that the buses were problematic when they bought them, but they accepted them anyway on the condition that the manufacturer would fix the defects before the buses were delivered.

But when multiple small frame cracks first appeared in 2003, the CTA considered it obvious that those repairs were never made, so they stopped payment on the $102 million contract in 2004.

In 2008, NABI filed a Breach of Contract lawsuit. The CTA countersued, arguing that a recently-hired consultant's analysis reveals that the manufacturer never met the contractual requirements.

Rodriguez says the agency plans to send all the buses back to the Alabama-based manufacturer.